PCE DUO Controller problems.

[NightWolve]

While continuing to diagnose I developed a direct short somewhere that fries fuses on power up.  In the mean time I purchased a slightly beat up DUO from KC and just swapped my nicer shell to it.

Uh-oh, watch out, that's what happened with my SNES... The great Steve called it right in my case, but I learned too late before he could help me. One of your voltage regulators is possibly dying! I thought it was just "surges" and ran out of 1-2 amp fuses, used 3 amps, but it happened again and that's how I damaged one of the SRAM chips (High voltage got sent into the motherboard, I should've waited for my order of 1 amp fuses to arrive!). Then it wouldn't turn on at all, so I ultimately thought to desolder the 7805 regulator and do a 5 Volt mod bypass with a well-regulated power supply, so now it's like the USB standard running direct on a 5 VDC supply. Plug contacts have to be REALLY clean though. While I got the unit running again, it was not without graphical glitches due to permanent damage...

Anyway, continuous blowing of fuses on power up even at 2 amps (I know we talked about sticking with 1 if possible) could indicate one of the regulators is going bad and will die completely. You have a 5 Volt and a 8 Volt together, so I'd investigate the possibility that one of them is going bad. If you did nothing major when this started to occur, it was working, then all of a sudden it started doing this, then yeah, I'd look at that. If you did even more solder work after that chip, then maybe you caused the short, but if it just happened all of a sudden on a running unit albeit with minor sound problems, perhaps a regulator is going bonkers (and continuous blowing of fuses is an indicator).

P.S. *minibreaker over one-time fuses = cool.

[DeshDildo]

While continuing to diagnose I developed a direct short somewhere that fries fuses on power up.  In the mean time I purchased a slightly beat up DUO from KC and just swapped my nicer shell to it.

Uh-oh, watch out, that's what happened with my SNES... The great Steve called it right in my case, but I learned too late before he could help me. One of your voltage regulators is possibly dying! I thought it was just "surges" and ran out of 1-2 amp fuses, used 3 amps, but it happened again and that's how I damaged one of the SRAM chips (High voltage got sent into the motherboard, I should've waited for my order of 1 amp fuses to arrive!). Then it wouldn't turn on at all, so I ultimately thought to desolder the 7805 regulator and do a 5 Volt mod bypass with a well-regulated power supply, so now it's like the USB standard running direct on a 5 VDC supply. Plug contacts have to be REALLY clean though. While I got the unit running again, it was not without graphical glitches due to permanent damage...

Anyway, continuous blowing of fuses on power up even at 2 amps (I know we talked about sticking with 1 if possible) could indicate one of the regulators is going bad and will die completely. You have a 5 Volt and a 8 Volt together, so I'd investigate the possibility that one of them is going bad. If you did nothing major when this started to occur, it was working, then all of a sudden it started doing this, then yeah, I'd look at that. If you did even more solder work after that chip, then maybe you caused the short, but if it just happened all of a sudden on a running unit albeit with minor sound problems, perhaps a regulator is going bonkers (and continuous blowing of fuses is an indicator).

P.S. *minibreaker over one-time fuses = cool.

I honestly believe I caused a short somewhere.  I tried soldering in jumper wires here and there where I thought the sound circuit was dropping out.  I removed everything I had done but suspect a small drop of solder may have dripped somewhere it wasn't supposed to go.  On the other hand, with the way things have gone with this unit, I wouldn't be surprised if another component decided to fail while fixing something else.

[NightWolve]

Ah, well, whatever the case, that's a real bummer... You got robbed! You did one of the most difficult [de]soldering tasks that essentially separates the men from the boys, the pros from the hacks, etc. in replacing a chip with dozens and dozens of closely spaced pins and with success, but then it all went to hell just as you were about to cross the finish line of completion because you tried to tackle one last minor sound problem... Tsk tsk... Total victory was so close at hand, sooo close, but alas, instead you tasted total defeat and had to buy another unit... Did I capture it about right ?? :/



Here's the chip in question again... If you can successfully swap a chip like this, it's a marker that pretty much graduates you to the next level in terms of soldering skills I think. Well, again, that's too bad man. This saga is depressing and I prefer to hear success stories, but that's how it goes sometimes...

[SephirothTNH]

That's pretty hardcore, dude... It looks way WAY too difficult for the PPU or CPU on a SNES... I'd replace the whole unit if I thought that was the problem.

HAHA yeah I guess it is.  I'm not going to sit here all high and mighty and pretend like it was easy.  I could certainly do it again if I needed to but would rather not. 

I will soon finally attempt replacement of one of the SRAM chips on my SNES... It was damaged as the 7805 voltage regulator was dying and sent high voltage to the motherboard. The SRAM pins are far enough spaced and it seems workable. I was thinking of using Steve's method with a halogen lamp to desolder one off of the Sony Sound module that BlueBMW sent me. I don't trust the chips on the motherboards he sent me, but it looks like the same type of 32K x 8 bit SRAM chip is used in the sound module, so that's probably the best place to take one from.

If that doesn't work for you let me know.  I've got two confirmed working sram chips off a dead motherboard I would gladly send you.

[NightWolve]

Ah, that's a neat trick, how do you confirm that they work ? Is that with logic probes ? I know Steve could do it, but we can't all be Steve. As there are 2 SRAM chips on a SNES motherboard, I have to flip a coin and choose one to desolder and replace... In other words, I'll have a 50/50 shot at either choosing the bad or good one. If I choose the good one, I'll have to do it all over again and add to the risk of further damage...

Can you confirm the SRAM chips used in the detachable sound module are compatible by chance with the ones on the motherboard ? They appear to be the same style visually and console5 seems to indicate as much:

http://console5.com/wiki/SNES#SHVC-CPU-01_.281990.29
http://console5.com/wiki/SRAM_256Kb:_32K_x_8-bit

[SephirothTNH]

No nothing so sophisticated.  I had a couple broken SNESs and one that worked but with graphics glitches on some games.  Naturally I suspected the video ram.  So I replaced them with the sram from the broken units with no change.  Eventually, after going through damn near every other component on the board, I tracked it down to a bad cpu and once replaced the system worked fine.  In the process I managed to weed out good and bad components from the broken systems.

It does look like those chips are compatible.  I looked up the data sheets on them and the pinouts were all standard.  I've seen both the Mosel MS62256, and the Sony CXK58257 used in the snes and they are both on that console 5 list.

[thesteve]

i did swap several SNES CPU and PPU using the halogen setup
the SNES has 1 SRAM work ram and 2 SRAM V-ram
and 2 more in the sound system